<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin:0;
            padding:0;
        }
        body{
            height:3000px;
        }
        div{
            height:100px;
            width:300px;
            background-color: red;
            margin-top:200px;
            /* 粘性定位，有兼容问题 */
            position: sticky;
            top:0;
        }
    </style>
</head>
<body>
    <div></div>
</body>
</html>